Generally in rotating machines, such as an electric motor, and a generator, rotation sensors using a Hall IC, a resolver and the like for detecting the rotational positions of rotational shafts are provided. Especially in hybrid powered vehicles, fuel cell powered vehicles, electric vehicles and the like intended for use in severe environments, resolvers of simple structure highly compatible to their environment are used, and control of the rotating machines is performed in accordance with the detected rotational position information.
A typical resolver for detecting a rotational position includes a resolver stator having an exciting coil for exciting a resolver rotor, a first detecting coil and a second detecting coil, and a resolver rotor connected to a rotating shaft.
Because the rotational position detection precision of the resolver is influenced by the patterns of windings of the first detecting coil and the second detecting coil, wire is wound precisely so as to be achieve a necessary measurement precision, and it is necessary to prevent this state from being disturbed by external force or the subsequent operation and the like. Therefore, care has to be taken on handling of it.
Japanese Patent Laid-Open Publication No. 2007-171131 (Patent Document 1) and Japanese Patent Laid-Open Publication No. 2007-192640 (Patent Document 2) each disclose art in which, in consideration of the above-noted factors, the area of the side surface of a resolver rotor extending in a diameter direction is configured to change with a change in the rotational position instead of the structure of winding a wire on a projected core opposed in the diameter direction to the resolver rotor from a resolver stator, and an annular coil board with an exciting coil, a first detecting coil and a second detecting coil being formed on the board as a coil pattern is used, whereby windings are formed precisely and reduction in thickness of a resolver main body is realized.